Known in the art is a method of preparing trans-,trans-,trans-1,5,9-cyclododecatriene by way of cyclotrimerization of butadiene at a temperature within the range of from 50.degree. to 200.degree. C. in the presence of a homogeneous catalyst including a compound of a bivalent nickel such as nickel acetylacetonate, and an organo-aluminium reducing agent such as (C.sub.2 H.sub.5).sub.2 AlOC.sub.2 H.sub.5 in a medium of an organic solvent.
The process occurs according to the following scheme: ##STR2## The yield of the desired product is as high as 75% by weight. Optimal temperature of the process is within the range of from 110.degree. to 120.degree. C.
This method, however, features a low selectivity and an insufficient yield of the desired product. Low selectivity of the process is revealed in the formation of cyclodimers of butadiene and its linear dimers and trimers. Furthermore, cyclotrimers are represented by a mixture of geometric isomers of trans-,trans-,trans- (I), trans-,trans-,cis- (II) and trans-,cis-,cis-cyclododecatrienes (III).
Also known in the art is a method of preparing trans-,trans-,trans-1,5,9-cyclododecatriene which comprises cyclotrimerization of butadiene at a temperature of 50.degree. to 250.degree. C. in the presence of a homogeneous catalyst containing a compound of bivalent nickel, an organo-aluminium compound and an activator in a medium of an organic solvent. As the activator use is made of pyridine. Addition of pyridine to the catalyst makes it possible to increase selectivity of the latter and, hence, increase selectivity of the process.
However, the yield of the desired product is 78% at the process duration of 12 hours at a temperature of from 110.degree. to 120.degree. C. Disadvantages of this prior art process also reside in a low yield of the desired product, long duration of the technological process. An essential disadvantage of the above-mentioned prior art methods resides in the use of hazardous organo-aluminium reducing agents.